No ring back tone SIP on external call forward

[Mstach]

Another SIP question. Mitel 3300ICP 5.0 when forwarding incoming SIP to an extrnal number via SIP, call will connect with two way adudio but during the connection there is no ring tone just dead air until it connects. Any thoughts?

 

[SXWizard]

In the COS of the SIP trunks in the General tab go to Call Hold and enable Music on Hold on Transfer.

 

[Mstach]

Thank you for your response. I just found out that it only happens when forwarding to cell phone numbers. I tested it by rerouting incoming SIP via outgoing sip to a ground line at my house and you can hear a ring back. Enabling MOH on transfer in Trunck COS did not make a difference

 

[LoopyLou]

Does it make a difference which cell provider they use?

I'd tell you a UDP joke but I'm afraid you won't get it. TCP jokes are the best because you always get them.